Append relative URL to java.net.URL

Question

Provided I have a java.net.URL object, pointing to let's say

http://example.com/myItems or http://example.com/myItems/

Is there some helper somewhere to append some relative URL to this? For instance append ./myItemId or myItemId to get : http://example.com/myItems/myItemId

Answer 1

You can use URIBuilder and the method URI#normalize to avoid duplicate / in the URI:

URIBuilder uriBuilder = new URIBuilder("http://example.com/test");
URI uri = uriBuilder.setPath(uriBuilder.getPath() + "/path/to/add")
          .build()
          .normalize();
// expected : http://example.com/test/path/to/add

Answer 2

UPDATED

I believe this is the shortest solution:

URL url1 = new URL("http://domain.com/contextpath");
String relativePath = "/additional/relative/path";
URL concatenatedUrl = new URL(url1.toExternalForm() + relativePath);

Answer 3

Some examples using the Apache URIBuilder http://hc.apache.org/httpcomponents-client-4.3.x/httpclient/apidocs/org/apache/http/client/utils/URIBuilder.html:

Ex1:

String url = "http://example.com/test";
URIBuilder builder = new URIBuilder(url);
builder.setPath((builder.getPath() + "/example").replaceAll("//+", "/"));
System.out.println("Result 1 -> " + builder.toString());

Result 1 -> http://example.com/test/example

Ex2:

String url = "http://example.com/test";
URIBuilder builder = new URIBuilder(url);
builder.setPath((builder.getPath() + "///example").replaceAll("//+", "/"));
System.out.println("Result 2 -> " + builder.toString());

Result 2 -> http://example.com/test/example

Answer 4

Concatenate a relative path to a URI:

java.net.URI uri = URI.create("https://stackoverflow.com/questions")
java.net.URI res = uri.resolve(uri.getPath + "/some/path")

res will contain https://stackoverflow.com/questions/some/path

Answer 5

You can just use the URI class for this:

import java.net.URI;
import org.apache.http.client.utils.URIBuilder;

URI uri = URI.create("http://example.com/basepath/");
URI uri2 = uri.resolve("./relative");
// => http://example.com/basepath/relative

Note the trailing slash on the base path and the base-relative format of the segment that's being appended. You can also use the URIBuilder class from Apache HTTP client:

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.3</version>
</dependency>

...

import java.net.URI;
import org.apache.http.client.utils.URIBuilder;

URI uri = URI.create("http://example.com/basepath");
URI uri2 = appendPath(uri, "relative");
// => http://example.com/basepath/relative

public URI appendPath(URI uri, String path) {
    URIBuilder builder = new URIBuilder(uri);
    builder.setPath(URI.create(builder.getPath() + "/").resolve("./" + path).getPath());
    return builder.build();
}

Answer 6

URL has a constructor that takes a base URL and a String spec.

Alternatively, java.net.URI adheres more closely to the standards, and has a resolve method to do the same thing. Create a URI from your URL using URL.toURI.